So, as I'm rewatching this, it occurs to me that Walt letting Jane die was indeed more about saving Jesse than him being an asshole. He was REALLY torn up about it, but let's not forget that Jane is the one that introduced Jesse to heroin and got him hooked on it. So, her dying "saved" Jesse. This was also directly after Walt talked to Jane's father and got the "There's nothing more important than family" line. Walt is looking at Jesse both as a way to save his immediate family and as Jesse becoming Walt's family.

I know this has been hashed out before, but it's something I never really let sink in the first time.